1. Field of the Invention
The invention relates to the field of satellite transmission antennas, possibly provided with receiving capacity. Such antennas are used in satellite broadcasting systems and they comprise a primary reflector and a source arm generally both connected to a support. The source arm may also be equipped with a secondary reflector.
The invention also relates to a satellite mobile telecommunications station. Satellite mobile telecommunications stations suitable for remote news gathering have recently become available, either transported in flight cases (Swe-Dish Fly-Away terminals, for example) or mounted on a vehicle (Swe-Dish Drive-Away terminals, for example). Such stations also have receiving capacities providing a bidirectional link.
2. Description of the Related Art
The uplink connection from a sender station to the satellite requires a high radiated power level in order for the signal rebroadcast by the satellite to be received and used correctly. To satisfy the required transmission power, in particular under extreme conditions (edge of satellite coverage, poor propagation channel), the sender station transmission system is provided with high-power amplifiers (HPA). Note that receive-only satellite antennas do not suffer from this power problem.
In satellite mobile telecommunications stations, these HPAs are in the form of a single unit combining one or more amplifier components (called active components, for example power transistors or traveling wave tubes (TWT)) and an appropriate power supply to provide the necessary and appropriate electrical power to the active components. These components are bulky and heavy if a power of tens or hundreds of watts is required, the resulting HPA weighing more than ten kilograms. This weight imposes high structural stresses on the elements supporting these components.
The invention also relates to the use of high-power amplifiers (HPA) based on traveling wave tubes (TWT) with a transmission power of at least 100 watts (W). A TWT-based HPA consists of a TWT subsystem and a high-voltage power supply subsystem producing voltages of several kilovolts. Generally designed as a one-piece unit, a TWT-based HPA incorporates a switch-mode power supply unit accepting direct current (DC) voltages (generally in the range 12 volts (V) to 48 V) or alternating current (AC) voltages (generally in the range 90 V to 265 V at 50 hertz (Hz) to 60 Hz) and supplying the high voltage necessary for the TWT to operate correctly.
It is known in the art to use fixed satellite antennas in which the HPAs are installed on the source arm of the antenna. The source arm is then sized appropriately to ensure the stiffness of the assembly and to maintain the centering of the secondary reflector or horn, such sizing sometimes being associated with the use of retaining rods or cables that relieve the source arm of the forces that are applied to it. These satellite antennas quickly become bulky and too heavy for mobile applications, in particular to conform to transportation standards such as those of the International Air Transport Association (IATA).